At the time of a conversation by telephone or the like, speech recognition, speech recording, and the like, it is preferable to collect a target speech (a voice of a user). Meanwhile, in some cases, a sound other than a target speech such as a background noise exists depending on a usage environment of a speech input device. Therefore, the development of a speech input device having a function that enables the device to reliably extract a speech of a user, i.e., which cancels the noise even in a case where the device is used in a noisy environment, has been advanced.
As a technology for canceling a noise in a noisy environment, providing sharp directivity to a microphone unit, or a method for canceling a noise such that directions of the incoming sound waves are identified by utilizing a difference in times of incoming sound waves, to perform signal processing, has been known (for example, refer to JP-A-7-312638, JP-A-9-331377, and JP-A-2001-186241).
Further, in recent years, the downsizing of electronics has been advanced, and the emphasis has been on a technology for downsizing a speech input device.